Navy surplus? Usually that conjures up images of knapsacks, peacoats and marine gear, not high-performance trimarans. However, the U.S. Department of Defense is auctioning off a 50-foot, three-hulled sailboat with a 40-horsepower diesel engine.

The fiberglass-hulled Contour 50 craft, now docked at Harbor Island, was used for “experimental purposes,” according to the liquidation services website.

Online bidding started Wednesday at $25 and had topped $8,200 by late afternoon at GovLiquidation.com. Bidding closes at 2 p.m. Friday.